Believe it or nicht, I only heard the word Zettelkasten yesterday, when I read a story by @acidic Andrew Macrae:
His brief article excited me enough to hunt down more information, and I bought the software he recommended.
I’m looking at a mountain-steep learning curve to work out the software, but thanks to your piece here, I have a paradigm to play with. I can relate everything back to your German scholar and his slips of paper.
The big advantage will be having a machine memory. You know the problem, I’m sure. You have something valuable — your passport, maybe — and you think “I mustn’t lose that!” and put it away in a safe place.
A year later when it’s almost time for the big overseas adventure, you want your passport and you know it’s in a safe place, but, um, where is that place?
The more files I stick on my computer or in Dropbox or wherever, the more time I’ve got to spend looking for them. Or was it iCloud? I’m sure I have an Evernote account somewhere. Or maybe on that hard drive I made sure I put in a safe place?